Metal ion-mediated molecular-imprinting polymer for indirect recognition of formate, acetate and propionate

In this paper, molecularly imprinted polymers (MIPs) of formic acid, acetic acid and propionic acid were studied firstly with 4vinylpyridine as functional monomer. The retention factors of these acids on their corresponding MIP columns were 0.028, 0.069 and 0.070, respectively. The results of no imprinting effect were explained and further discussed with the help of computer simulation. In order to specifically recognize these simple acids, we synthesized MIPs with 4-vinylpyridine as functional monomer and their complex as template, which is formed with formate (acetate or propionate) and picolinamide as ligands and copper (II) as central metal ion. Chromatographic evaluation showed that these MIPs had strong imprinting effect for their templates. The retention factors were improved to 25.9, 9.20 and 18.65, respectively. Only MIP from copper formate complex as template had no selectivity. Thus with the help of picolinamide and copper (II), formic, acetic and propionic acid could be recognized indirectly with MIPs synthesized. The method proposed here can be looked as a solution to the imprinting problem of some small and simple molecules which can form metal complexes. This type of MIP could be prepared in strong polar solvent because of the relative strong interaction between the template complex and the functional monomer.